chapter 4: composite pre-processing - altair...

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Chapter 4: Composite Pre-Processing


Agenda – Chapter 4: Composite Pre-Processing

4. Modeling of Composites in Finite Element Environments

4.1 Ply-Based Laminate Modeling Concept

4.2 How to Setup Composites in HyperMesh

4.3 Designing Composite using HyperLaminate

Exercise 4.1 PCOMP

Exercise 4.2 PCOMPG

Exercise 4.3 PCOMPP


Chapter 4: Modeling of Composites in Finite Element Environments







Exercise 4.1 PCOMP

Exercise 4.2 PCOMPG

Exercise 4.3 PCOMPP


Chapter 4: Modeling of Composite

Modeling of Composites in Finite Element Environments

Composites can be modeled using single layer shells, multi-layer shells

(continuum shells) and/or solids.

In case of solids, each ply needs to be modeled with at least one solid

element. This requires a huge number of solid elements to model a simple

plate.

Majority of the real life parts are modeled with single layer shell elements.

Analysis of composite shells is very similar to the solution of standard shell

elements. An single layer shell element is modeled as composite by assigning a composite property (e.g. PCOMP, PCOMPG or PCOMPP) to it.

Composite material properties in general are modeled with an orthotropic

material model (e.g. MAT8 - NASTRAN Solver ).


Core 10 mm

2 mm

2 mm

Sandwich Modeling Idealization

Core: Isotropic

• E = 20 MPa

• G = 0.45

Plies: Isotropic

• E = 73,000 MPa

• G = 0.18


PCOMP3 Layers

PSHELL

PSOLID

PSHELL

PSHELL

PSOLID

PSHELL



Displacement plot

PCOMP

3 layers

PSHELLPSOLID

PSHELL

PSHELLPSOLID

PSHELL



RADIOSS shell elements use FSDT.

Even for thick shell, the hypothesis that a straight line normal to the middle plane remains straight still holds.

In reality, with a soft solid in the middle, the actual deformation is more ‘zigzag’.

Subdividing the solid into 3 layers is not very beneficial here - one solid with two shells suffices to approximate the above ‘zigzag’.



Chapter 4.1: Ply-Based Laminate Modeling







Exercise 2.1 PCOMP

Exercise 2.2 PCOMPG

Exercise 2.3 PCOMPP


Different choice for PROPERTY definitions – PCOMP

• Homogenization performed in preprocessor

• No associativity between PCOMPs

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

PCOMP PID Z0 NSM SB FT TREF GE LAM

MID1 T1 THETA1 SOUT1 MID2 T2 THETA2 SOUT2

MID3 T3 THETA3 SOUT3 etc. …

… …

DS

Ply-Based Laminate Modeling Concept


Different choice for Property definitions - PCOMPG

• Homogenization performed in preprocessor

• Some associativity between PCOMPs

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

PCOMPG PID Z0 NSM SB FT TREF GE LAM

GPLYID1 MID1 T1 THETA1 SOUT1

GPLYID2 MID2 T2 THETA2 SOUT2

… … …

DS




Different choice for PROPERTY definitions - PCOMP - PCOMPG


Different choice for PROPERTY definitions – PCOMP

PCOMP defines all the laminate properties like ply material, thickness and orientation and also the stacking sequence in ONE Property Card.

PCOMP definition contains no information on plies that are also part of

other regions (PCOMPs). During post-processing, this requires lot of book keeping to track ply and stacking information for each PCOMP.

Chapter 2: Composite Pre-processing - Analysis


Different choice for Property definitions - PCOMPG

PCOMPG is similar to PCOMP and additionally it stores global ply identification number.

Through the global ply identification number, plies that are part of many regions can be tracked across the regions, reducing the effort for keeping track of the ply properties and stacking information.




Current “Zone-Based” or “Section-Based” approach


Current “Zone-Based” or “Section-Based” approach

• Treating laminated composites like metals

• Ignoring ply-based nature of laminated composites



Current “Zone-Based” composite modeling approach

Disadvantages

• 5 Plies in this simple example create 9 Zones (data to be handled)

• Ply thicknesses are not interconnected (so a thickness change can be a

large book-keeping effort)

• Adding a new ply requires re-zoning effort, which can be considerable



Current “Zone-Based” composite modeling approach

Adding an new ply requires much effort in re-zoning elements and re-meshing

is often required.




New ply-based composite modeling approach


PLY - Card

STACK - Card

PCOMPP - Card

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

STACK ID LAM PLYID1 PLYID2 PLYID3 PLYID4 PLYID5 PLYID6

PLYID7 …

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

PLY ID MID T THETA SOUT TMANUF

ESID1 ESID2 ESID3 ESID4 ESID5 ESID6 ESID7 ESID8

ESID9 …

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

PCMOPP PID Z0 NSM SB FT TREF GE



PLY - Card

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

PLY ID MID T THETA SOUT TMANUF


ESID9 …



STACK – Card

Please show and explain : HW10.0 HELP – Stack Card

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

STACK ID LAM PLYID1 PLYID2 PLYID3 PLYID4 PLYID5 PLYID6

PLYID7 …



PCOMPP - Card

• dummy property to facilitate handling

• also used to define some more global parameters (Z0, TREF, FT)


(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

PCMOPP PID Z0 NSM SB FT TREF GE


Ply-Based Laminate Modeling Concept• PLY – Global Ply Data and Elements Defining Global Ply

• STACK - “glues” PLYs into a Laminate with Order

• PCOMPP – implicit through STACK and PLYs (replacing PCOMP/G)

PLY 1 MID THK THETA SOUT ELEMENTs (e.g. 0° )

PLY 2 MID THK THETA SOUT ELEMENTs (e.g. 90°)

PLY 3 MID THK THETA SOUT ELEMENTs (e.g. 0° )

PLY 4 MID THK THETA SOUT ELEMENTs (e.g. 45°)

PLY …

STACK 1 SYM PLY1 PLY2 ….




Left flange [11 12 13 14 21 22 23 24]Right flange [11 12 13 14 31 32 33 34]Web [24 23 22 21 41 42 43 31 32 33 34]

Conflicting stacking sequences!

STACK 100

+ SUB 1 top 11 12 13 14

+ SUB 2 left 21 22 23 24

+ SUB 3 right 31 32 33 34

+ SUB 4 mid 41 42 43

+ INT 14 21

+ INT 14 31

+ INT 21 41

+ INT 43 31

STACK Card – SUBlaminate & INTerfaces

• Required to model structures such as T- or I-Beams where the stacking sequence cannot be uniquely defined by a simple STACK card

• Intuitive definition reflecting the manufacturing process


STACK Card – SUBlaminate & INTerfaces

• Substacks (SUB) define partial stacking sequences

• Interfaces (INT) indicate how the substacks are assembled

• During ply stacking optimization, substacks are shuffled independently as to avoid undesirable ‘penetration’ effects


STACK 100

+ SUB 1 top 11 12 13 14

+ SUB 2 left 21 22 23 24

+ SUB 3 right 31 32 33 34

+ SUB 4 mid 41 42 43

+ INT 14 21

+ INT 14 31

+ INT 21 41

+ INT 43 31


STACK Card – SUBlaminate & INTerfaces• Supported as control card

• PLY based composite entities

• To create multiple STACKs use pull-down or solver browser

Setup -> Create -> Stack



Draping accommodation

• Each element may be assigned ∆θ and ∆T for each ply individually

PLY – Card

DRAPE - Card

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

PLY ID MID T THETA SOUT TMANUF DRID


ESID9 …


(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

DRAPE DRID


DRAPE – Card

• Draped half-sphere after importing data from ANAGLYPH Laminate Tools


(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

DRAPE DRID

ELEM 123 1.000000 90.55610







Exercise 4.1 PCOMP

Exercise 4.2 PCOMPG

Exercise 4.3 PCOMPP


Chapter 4: Composite Pre-processing

How to Setup a Composite in HyperMesh (I)

1. Import or create the 2D geometry that will represent your component.

2. Organize your model in components

3. Generate the Mesh.



How to Setup a Composite in HyperMesh (II)

4. Align the elements according to the laminate main direction

• TETA (Angle that the element needs to be rotate from definition)

• MCID (Local coordinate system)

• Both are defined as the (7th field for CQUAD or 6th field for CTRIA)

5. Define the composite materials.

Don’t forget about the normals !!!



How to Setup a Composite in HyperMesh (III)

6. Define the PCOMP , PCOMPG or PCOMPP* properties

* inclusive PLY and STACK cards

PCOMP (1 mm) [45, 90, -45]S

PCOMPG (1 mm) [45, 90, -45]S



How to Setup a Composite in HyperMesh (IV)

7. Assign the properties to the components.

8. Apply the boundary conditions. (SPC)

9. Apply the loads. (Load)

Loads applied to

geometry to simply the

display !!!



How to Setup a Composite in HyperMesh (V)

10. Create the load step with the constraints and loads.

11. Run the analysis

12. Post-processing


Composite Pre-Processing – In Detail



Parameters for modeling composites

Define material properties (MAT8)

• Ply, matrix and core (HOMOGENIZATION)

Define the material coordinate system to establish the reference for defining

the ply angle

Define the element normal to establish the reference for defining ply stacking

Define the individual laminate property (PCOMP)

• Ply material, Ply thickness (number of plies), Ply angle, Order of stacking



Modeling Flow

Element(CQUAD4 )

Element Property(PCOMP)failure theory

Material Property(MAT8)

Material Orientation

Element Normal



The typical material model used for composites is MAT8, which is planar

orthotropic material.

Each ply is associated with a material property.

The use of isotropic MAT1 or general anisotropic MAT2 for ply properties is also supported.




Definition of material property, MAT8 in Hypermesh

E1 = 18.7e6 psi υ12 = υ13= 0.3 G12 = G13 = 0.5e6psi a1 = 1.0e-7 in/in/oC

E2 = E3 = 1.4e6 psi υ23 = 0.6 G23 = 0.45e6 psi a2 = a3 = 18.0e-6 in/in/oC




Example of a typical composite property is,

Element Property(PCOMP)

PCOMP Property Failure Theory

Ply 3

Ply 1

Ply 4

Ply 2



Element’s normal direction defines the stacking sequence.

Plies are listed from the bottom surface upwards, with respect to the

element’s normal direction

Element Normal



• The material orientation is important to establish the reference for ply angles. Ply angles can be specified relative to a

a) element coordinate system,

b) vector projected onto elements,

c) coordinate system.

• Since element coordinate system is strongly dependent upon the node

numbering in individual elements, it is advisable to prescribe a coordinate system for composite elements and specify ply angles relative to this

system.





• 2D -> composites panel, allows the user to define, review or modify the

material orientation for elements.

• Individual ply orientation can also be reviewed by selecting ply number.

Material Orientation by default(based on element node numbering)

Material Orientation by specifying Material orientation angle


Sample material property is defined as E1 = 1.3e5 Mpa E2 = E3 = 9650 Mpa

υ12 = υ13 = 0.3 υ23 = 0.6

G12 = G13 = 3450 Mpa G23 = 3100 MPa

a1 = 1.0e-7mm/mm/oC a2 = a3 = 18.0e-6 mm/mm/oC

E1 is much stronger than E2 . But, in which directions are E1 and E2 measured?

Material orientation is very important because it defines the direction for E1 and

E2. It also establishes the reference for the definition of ply angle.

Why is Material orientation is very important?




Why is Material orientation is very important?


Understanding different coordinate systems

There are many coordinate systems like:

• global coordinate system,

• local coordinate systems,

• element coordinate systems,

• material coordinate systems, …

There is always only one global coordinate system which is the reference

for all other coordinate systems.

Direction for E1 is the x-axis of the element’s material coordinate system

and direction for E2 corresponds to its y-axis.



Understanding the element coordinate system

For anisotropic elements by default the material coordinate system is aligned with the element coordinate system.

The x-axis of the element coordinate is aligned with side 1-2 (or direction

from G1 → G2) of the shell element and z-axis is aligned with the normal

of the shell element.



Material coordinate system

• Material orientation by default (based on element node numbering) may not

be aligned properly.

• Material coordinate system should be

defined to align the E1 and E2 to the desired

direction.

• Material coordinate system can be defined

by defining an angle or a

coordinate system.



Material coordinate system

Material orientation can be defined as an angle Rotated by THETA from the

x axis of the element coordinate system.

THETA = 90 degree

• X (G1 → G2) Rotated by THETA

• Z = Element Normal

• MCID: X is defined by the local coordinate system.








Exercise 2.1 PCOMP

Exercise 2.2 PCOMPG

Exercise 2.3 PCOMPP


Special features for composite laminates

Designing using HM HyperLaminate


Designing using HM HyperLaminate







Exercise 2.1 PCOMP

Exercise 2.2 PCOMPG

Exercise 2.3 PCOMPP


Altair HyperWorks 10.0: A Platform for Innovation

chapter 4: composite pre-processing - altair...

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